Permeation of Inward Rectifier K+ Channels

描述(申请人提供)：我研究的长期目标是 了解K关于经络的机制，一组高度多样化的 完整的膜蛋白。一类特殊的K+通道，称为Inside About 整流器向内传递K+离子比向内传递K+更有效 向外的方向。这一属性称为向内整流，允许 维持和调节静息膜的内向整流钾通道 并因此完成许多重要的生物学任务。这个 这里提出的实验主要是为了了解这些机制。 潜在的向内整流，即通道是如何被 细胞内的阳离子。 这些通道将在非洲爪哇卵母细胞中表达，并将其功能 将使用电生理技术在 结合诱变。目标1：了解内向的机制 通过细胞内阳离子的整流阻断，我们将确定：a)动力学 胞内多胺阻断通道的机制，b)其作用机制 赋予内向整流器与 细胞内的多胺，以及c)潜在的分子机制 通道对细胞内阳离子的专一性。在目标2中，我们将使用 细菌钾离子通道(KCSA)的传导孔-其结构已被 用X射线衍射法测定--作为进一步研究机理的模型 通过该通道实现细胞内的高亲和力结合 阳离子。 拟议的研究具有重要的医学意义。内向整流K+ 通道发挥着许多重要的生物学作用，例如，它们是调节控制的媒介 迷走神经调节心率，调节神经中的突触传递 系统，并将血糖水平与胰岛素分泌挂钩。因此，这些 经络是医学干预的重要药理靶点 在各种疾病状态下。

DESCRIPTION (provided by applicant): The long term goal of my research is to understand the mechanisms of K about channels, a group of highly diversified integral membrane proteins. A special class of K+ channels, called inward about rectifiers, pass K+ ions in the inward direction more efficiently than in the outward direction. This property, referred to as inward rectification, allows inward-rectifier K+ channels to maintain and regulate the resting membrane potential and thereby accomplish many important biological tasks. The experiments proposed here are primarily aimed to understand the mechanisms underlying inward rectification, i.e., how the channels are blocked by intracellular cations. The channels will be expressed in Xenopus oocytes and their functional properties will be examined using electrophysiological techniques in conjunction with mutagenesis. Aim 1: To understand the mechanisms of inward rectifier block by intracellular cations we will determine: a) the kinetic mechanism of channel block by intracellular polyamines, b) the mechanism which confers high affinity to the interaction of inward rectifiers with intracellular polyamines, and c) the molecular mechanism underlying the channel's specificity for intracellular cations. In Aim 2, we will use the conduction pore of a bacterial K+ channel (KcsA)-whose structure has been determined with X-ray diffraction-as a model to further examine the mechanism by which the channel achieves the high-affinity binding of intracellular cations. The proposed studies have important medical implications. Inward-rectifier K+ channels play many important biological roles, e.g., they mediate the control of heart rate by the vagus nerve, modulate synaptic transmission in the nervous system, and couple blood glucose levels to insulin secretion. Thus, these channels represent important pharmacological targets for medical intervention during various disease states.